1. Field of the Invention
This invention relates to refractory assemblies and components thereof for use in industrial furnace roofs. More particularly, this invention relates to roof assemblies and components particularly suitable for repairing suspended refractory brick roofs.
2. Description of Prior Art
Refractory bricks are used in roof construction of high temperature industrial furnaces such as reverberatory furnaces. In furnace roof construction, the refractory bricks are suspended from a support structure which may be from several inches to about 2 feet above the brick roof. The refractory bricks are suspended from the support structure by various suspending means such as metallic hangers which hold the bricks at one end and hook over the support structure at the other end. Reverberatory furnaces are frequently operated for many years without shutdown. However, the life of the suspended roof which is usually constructed from refractories is from 6 months to 3 years. This makes patching of the roof furnace during operation necessary. Some roof refractory structures are panelized so that entire sections may be removed and replaced, or individual pairs of bricks in the panel may be patched by use of assemblies of this invention. In roofs which are not panelized, the roof is constructed by placement of individual or pairs of bricks. The assembly of this invention may be used, as well, in repair of non-panelized furnace roofs.
The refractory bricks used in high temperature furnace construction have a rectangular cross-section. Normally, in patching refractory roofs, two bricks are assembled with a hanger supporting both bricks in the patching assembly. The cross-section of the patching assembly is rectangular, normally occupying a space of 41/2 by 7 inches. When patching the refractory roof, the opening for the patch assembly may have a long dimension which runs parallel to the longitudinal center line of the furnace or at right angles to it, depending upon the shape of the hole to be patched. The support structure, whether panelized construction is used or individual pairs of bricks are used, normally runs at right angles to the center line of the furnace.
Most patching or repair assemblies previously available, due to the opening being greater in one dimension than the other, require use of two types of assemblies. Since the plane of the hook of the hanger and the long dimension of the brick patching assembly were not rotatable with respect to each other, it has been necessary to provide one assembly with a hanger hook for attachment to the support structure parallel to the long dimension of the patch assembly and one with the hanger hook at right angles to the short dimension of the patch assembly. Therefore, it has been necessary to provide more than the required number of patch assemblies at the job site because it is not usually known until engaging in the repair which way the patch assembly will be introduced into the furnace. One approach to overcoming this disadvantage and utilizing patch assemblies having a hanger with a hook which may be used in both directions has been to provide a hanger with a mushroom-shaped head loosely fitting on the hanger casting recess, thereby allowing the hanger hook to rotate 360 degrees with respect to the bricks. This eliminates the inventory problem, but creates serious disadvantages in use because the refractory is free to rotate on the end of the hanger thereby making it difficult to insert the patch into the hole in the hot furnace roof, especially in cases where the patch must be inserted at an angle. Many of the same problems arise in new furnace construction.
These problems are solved by the industrial furnace roof assembly of our earlier U.S. patent, U.S. Pat. No. 4,073,243 which teaches an industrial furnace roof assembly in which brick pairs are suspended by an assembly of a hanger which mates with voids in both bricks, and a hanger rod which supports the hanger. The hanger has a square, upset-forged head which serves as the bearing surface for the hanger. The hanger rod passes through a hole in the hanger and is bent to form a hook which can be hung from a supporting member such as a pipe. In accordance with the '243 patent, the hanger rod is first passed through the hole in the hanger. The hanger, with the hanger rod engaged, is then seated into the void of one brick. A second brick is placed against the first brick such that the casing and hanger are at the split line of the two bricks. It is very common for an assembly of bricks, hanger and hanger rod to be encased in a steel casing and shipped as a complete assembly.
However, material handling of brick assemblies as taught by the '243 patent is complicated by the irregularity of the assembled brick pair with the hanger rod protruding out from the brick. Special care must be taken during packaging to assure that the bricks are properly supported without damage to the hanger rods. In addition, brick assemblies require more storage space.